根据字母顺序索引重复字符串中的字符

const range = (start, stop, step) =>
  array.from(
    { length: math.ceil((stop - start) / step) },
    (_, i) => start + i * step
  );

const upperalpha = range("a".charcodeat(0), "z".charcodeat(0) + 1, 1).map((x) =>
  string.fromcharcode(x)
);

const loweralpha = range("a".charcodeat(0), "z".charcodeat(0) + 1, 1).map((x) =>
  string.fromcharcode(x)
);

function getalphaindex(char) {
  if (char === char.touppercase()) {
    return upperalpha.indexof(char) + 1;
  }

  if (char === char.tolowercase()) {
    return loweralpha.indexof(char) + 1;
  }
}

function repeatalpha(text) {
  let occurrence = [];

  array.from(text).foreach((char) => {
    let count = getalphaindex(char);
    let result = array(count).fill(char).join("");
    occurrence.push(result);
  });

  return occurrence.join("");
}

console.log(repeatalpha("becky"));
console.log(repeatalpha("nengi"));
console.log(repeatalpha("chinwendu"));
console.log(repeatalpha("dindustack"));

BBeeeeeccckkkkkkkkkkkyyyyyyyyyyyyyyyyyyyyyyyyy
nnnnnnnnnnnnnneeeeeNNNNNNNNNNNNNNgggggggiiiiiiiii
CCChhhhhhhhIIIIIIIIInnnnnnnnnnnnnnwwwwwwwwwwwwwwwwwwwwwwweeeeennnnnnnnnnnnnndddduuuuuuuuuuuuuuuuuuuuu
ddddiiiiiiiiinnnnnnnnnnnnnndddduuuuuuuuuuuuuuuuuuuuusssssssssssssssssssttttttttttttttttttttaccckkkkkkkkkkk